The invention relates to forming fabrics for use with paper making machines. In use, the forming fabric is moved through the papermaking machine at speeds in excess of 2000 meters per minute while passing over suction boxes and rollers. Because of the contact with the suction boxes, is only with the outer areas of the forming fabric, excessive wear occurs in these areas. The fabric of the invention reinforces these outer areas.
Numerous attempts have been made to eliminate this problem. One such attempt is taught in the arrangement of U.S. Pat. No. 4,917,937 where molten plastic is applied to the surface of the forming fabric as a plurality of configured rows of plastic material. This patent does not disclose a particular plastic nor does it disclose having the plastic forced into the interstices of the forming fabric to bond with the internal warp and weft yarns constituting the forming fabric.
U.S. Pat. No. 5,084,326 is also directed to providing abrasive resistant areas adjacent opposed edges of a forming fabric. The '326 patent discloses applying strips of abrasion resistant plastic material incorporated with a melting adhesive to opposed edges of the forming fabric in various spaced patterns. The abrasive material only partially penetrates the forming fabric and is secured thereto by the adhesive incorporated therewith. The abrasion resistant material which is a polyester or polyamide mixed with a melting adhesive may be in the form of threads or particles.
German Patent application (DE-052922025) is directed to almost the same subject matter as the '326 patent referred to above. Here a paper forming fabric has wear resistant areas formed by applying a wear resistant plastic or polymer at wear areas. The materials disclosed are polyamide and polyester; no polyurethanes. The reference discloses the use of formaldehyde resin which acts with the above plastics as an adhesion promoter.
The instant invention has as its object to provide a forming fabric for a papermaker's machine having abrasion resistant zones along longitudinal edge portions of the fabric.
Another object of the invention is to provide a forming fabric with abrasion resistant areas and yet have substantially undiminished dewatering properties.
Another object of the invention is to provide a forming fabric having abrasion resistant areas capable of withstanding the temperatures and operational speeds at which the fabric must function.